Waste yeast discharged from food production plants such as breweries is subjected to waste treatments by incineration or the like, except for part of the waste yeast being used as raw materials for yeast extracts and yeast preparations, feeds for livestock, fertilizers, and the like. Meanwhile, some of yeast cell walls remaining after extraction of yeast extracts are used for health foods, feeds for livestock, and the like while the rest of the yeast cell walls is mainly discarded.
However, the waste treatments of these microorganism-derived materials entail costs of transport to disposal sites and disposal costs. In addition, in the cases of the above-described conventionally known foods, animal feeds, fertilizers, and the like derived from yeast, some limitations exist in terms of the amount of the waste yeast used relative to the amount of the waste yeast generated, and the like. Hence, there is a need for a new application of waste yeast by which the waste yeast can be provided as a high-value added product.
As a new application of the use of the waste yeast, for example, Patent Literature 1 discloses a method for producing a microorganism-derived reducing mixture having an oxidation-reduction potential of 0 mV or less, the method comprising subjecting a microorganism or a component of a microorganism to a hydrothermal reaction treatment in the absence of oxygen.
Fruit trees, especially, Mikan (Citrus unshiu), kaki persimmon (Diospyros Kaki), and the like often bear poorly because of shortage of nutrients in the year after they bear heavily, so that almost no fruits can be harvested in the year (biennial bearing). The propensity to the biennial bearing is higher especially in cultivars, such as Citrus unshiu, which mature late. Disbudding, fruit thinning, pruning, and the like are conducted to prevent the biennial bearing. However, these entail labor and labor costs, but cannot prevent the biennial bearing radically.
The biennial bearing phenomenon occurs frequently in outdoor growing. Hence, recently, annual bearing in which fruits are borne every year has been made possible to some degree by carefully controlling fertilization and growing in greenhouse growing. However, the greenhouse growing entails enormous costs for constructing the greenhouse and for controlling the temperature and water in the greenhouse. Hence, the prevention of the biennial bearing by greenhouse growing is not widely spread under the current situation.
Moreover, citrus fruits such as Dekopon have strong sour taste, and hence cannot be shipped until the acidity decreases. In this respect, conventional citrus fruits, especially outdoor-grown citrus fruits cannot be shipped early, and are shipped generally two to three months later than those grown in facilities. The early shipment of outdoor-grown citrus fruits enables the fruits grown outdoor at low costs to be sold at high prices, and hence a great increase in profit can be expected.